In residential house construction and as is well known, the plumbing is basically installed in three stages, namely, the rough-in plumbing, top-out plumbing and finish plumbing. The rough-in plumbing occurs prior to pouring of concrete. Top-out plumbing follows framing the building and involves installing the pipes in the walls and vent pipes that extend up through the roof of the structure. Finish plumbing relates to setting toilets, sinks, and the like.
The rough plumbing includes laying a drain or waste pipe which leads from building to the city sewer main normally in the access street or road adjacent to the building. It is common practice to insert a clean-out in the drain pipe between the pipes in the building and the section of the drain pipe that leads to the sewer line. This clean-out may be located in a basement or, in a building without a basement, outside the building and underground. If underground, the clean-out has a branch extending to the surface of the ground for providing access to the drain pipe both during construction and during use of the building.
As is well known, in order to pass the rigid inspection normally imposed by building codes, it is necessary to test the drainage part of the plumbing system after the rough-in and top-out stages are finished. For this purpose, common procedures and devices are in use. The devices include test caps and inflatable test plugs, so-called water-weenies. In use, the test caps are sealed at the ends of all open and exposed branch pipes, and the inflatable test plugs are used in the clean-out where the passageway plugged is not as accessible. After the tests, the exposed test caps are punched out with a hammer, and the inflatable plugs are deflated and pulled out of the clean-out. Thus, the test plugs and the inflatable plugs can be removed without disassembling and disturbing the tested system.
As indicated, the test caps in above-ground, accessible locations are usually knocked out with a hammer, whereupon the fragments are pried out with a screwdriver or pliers. If a test cap were sealed in a clean-out, however, whether the clean-out is relatively accessible in a basement or whether it is underground, it cannot be punched out with a hammer and screwdriver without disassembling part of the system and thereby disturbing the tested system. Thus test caps have not been used to block the test pressure in the drain pipe.
Instead, during the rough-in plumbing stage the inflatable weenie-shaped, test plugs have been inserted in the clean-out, used for the tests and subsequently removed with a pull chain attached to the plug and extending out of the clean-out. More specifically to test the rough-in plumbing the plug is inserted and inflated thereby sealing the drain pipe. The plumbing on the building side of the plug is then pressurized to check for leaks. After the top-out phase is completed the plumbing is again tested by again inflating the plug, and pressurizing the system, usually by feeding water into the system through the vent pipes in the roof.
Use of such inflatable weenie plugs for the described testing has proved unsatisfactory for several reasons. The essential problem is that the plugs often leak although the plumbing may be entirely sound. Either the plug does not seal perfectly circumferentially within the pipe or the plug is punctured as it is being slid in or out of the clean-out and against the rough surfaces thereof. As a result, the test fails, not because of faulty plumbing, but because of a faulty plug, the plumbing crew will then need to be called back to the job to attend to the problem, causing aggravation and extra expense to the contractors and owners involved. Not only is there extra labor cost involved, hut the failed inflatable test plugs must be replaced at considerable expense.